Taxonomic inventories and assessments of terrestrial snails on the ...

Taxonomic inventories and assessments of terrestrial snails on the ... Taxonomic inventories and assessments of terrestrial snails on the ...

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Table 3. Mean densities ong>ofong> extant ground-dwelling ong>snailsong> at three sites in Tinian. Densities are presented as mean ± S.D. in four 0.25-m 2 quadrat samples at each site, except for Lamellidea sp., with is the count from one 25-m 2 quadrat. Total numbers ong>ofong> ong>snailsong> are given in parentheses. Hagoi Mt. Lasu Mahalang Georissa biangulata --- --- 0.25 ± 0.50 (1) Georissa elegans 1.50 ± 0.58 (6) 1.5 ± 0.14 (2) 1.50 ± 1.29 (6) Georissa laevigata 25.75 ± 22.32 (103) 25.25 ± 10.24 (101) 31.50 ± 33.67 (126) Palaina taeniolata --- 1.50 ± 3.00 (6) --- Paropeas achatinaceum --- --- 14.00 ± 2.94 (56) Subulina octona --- 0.25 ± 0.50 (1) --- Elasmias quadrasi --- 0.25 ± 0.50 (1) --- Lamellidea sp. 8.00 (8) --- --- Mean shell sizes for Georissa laevigata occurring at Hagoi, Mt. Lasu, ong>andong> Mahalang are presented in Figures 13, 14, ong>andong> 15, respectively. Mean shell sizes for Paropeas achatinaceum at the Mahalang study site are provided in Figure 16. Aguiguan No living Partula gibba or Partula langfordi were observed at any ong>ofong> the seven sampling stations or any ong>ofong> the forested areas investigated in Aguiguan during this survey. Sun-bleached shells ong>ofong> Partula gibba were at the surface or in leaf litter at five ong>ofong> the seven sites sampled, including those previously studied by Craig ong>andong> Chong>andong>ran (1992) ong>andong> Smith (1995). Dead shells ong>ofong> Partula langfordi were found at only two ong>ofong> the seven sites. Shells ong>ofong> both species lacked the color ong>andong> luster ong>ofong> shells ong>ofong> live ong>snailsong> or recent mortalities, leading to a conclusion that the observed shells are very old. A summary ong>ofong> species ong>ofong> dead ground shells observed during this survey is given in Table 4. Only four species in two families ong>ofong> ground-dwelling ong>snailsong> were found living in 8 m 2 ong>ofong> forest floor sampled in Aguiguan. Three ong>ofong> these species dominated at Site 5, ong>andong> two species at Site 6 (Table 5). Palaina taeniolata reached the highest mean density at 80.9 ong>snailsong>/m 2 at Station 5, while Georissa laevigata was more evenly distributed between the two sites. Palaina hyalina reached moderate densities at Site 5, but only a single individual was found at Site 6. A total ong>ofong> only two Georissa biangulata were encountered, both at Station 6. 14

Figure 8. Size-frequency distributions ong>ofong> Georissa laevigata in four 0.25- m 2 quadrats at the Hagoi sampling station. Figure 9. Size-frequency distributions ong>ofong> Georissa laevigata in four 0.25- m 2 quadrats at the Mt. Lasu Hagoi sampling station. 15

Figure 8. Size-frequency distributi<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> Georissa laevigata in four 0.25-<br />

m 2 quadrats at <strong>the</strong> Hagoi sampling stati<strong>on</strong>.<br />

Figure 9. Size-frequency distributi<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> Georissa laevigata in four 0.25-<br />

m 2 quadrats at <strong>the</strong> Mt. Lasu Hagoi sampling stati<strong>on</strong>.<br />

15

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